CN214591151U - Current control type switching power supply circuit, LED lighting circuit, and lighting apparatus - Google Patents

Abstract

The application relates to a switching power supply, and provides a current control type switching power supply circuit, an LED lighting circuit and a lighting device, wherein the switching power supply circuit comprises a switching power supply (100) with a power switch (M1) and a energy storage and release element (L1); and a current sensing element (R3) for detecting a magnitude of current corresponding to the outputted energy; a control chip (200) that controls a switching operation of the power switch (M1); the control chip (200) includes a voltage feedback input (FB); the voltage feedback input (FB) is connected to Ground (GND) via a first capacitor (C1); and to the output (3) via a compensation network (400). Therefore, a right half-plane zero point is provided, the phase margin of the switching power supply (100) is increased, the gain margin and the crossing frequency of the switching power supply are reduced, and the constant-current PFC switching power supply based on the voltage control type chip can stably work.

Description

Current control type switching power supply circuit, LED lighting circuit, and lighting apparatus

Technical Field

The present application belongs to the field of switching power supplies, and more particularly (GND) relates to a current control type switching power supply circuit, an LED lighting circuit, and a lighting device.

Background

In a typical switching Power supply application, single-stage constant current Power Factor Correction (PFC), which is an efficient and cheap loop control method, has an important application value in a low-current lighting device. Because the output of the switching power supply is constant current, the design of the control loop is different from that of the switching power supply with constant voltage output.

Generally, high frequency operation is widely adopted in the miniaturized design of the switching power supply, and with the development of gallium nitride and silicon carbide elements, the control manner of the high frequency operation becomes more and more common. In a low-operating frequency critical Conduction Mode (BCM) PFC switching power supply design, some Constant Current (CC) controllers/chips may be used, but in a high-frequency application, no adaptive CC controller is currently available. Therefore, Constant current control is generally implemented by some processes on the basis of a conventional Constant Voltage (CV) controller/chip that supports a high operating frequency. In the utility model, the voltage/constant voltage control type controller/chip means that the original factory design of the controller/chip is to adjust the output voltage of the switching power supply; and the current/constant current type control means that the output current of the switching power supply is regulated. In LED lighting, LED driving generally requires current control because the LED intensity is more closely related to current.

As shown in fig. 1, a typical external circuit design using a constant voltage controller to realize constant current control, a resistor R3 is used to sample the average LED current for feedback control. In conjunction with fig. 2, C2, C7, R5 (or C2 alone) make up an internal Operational Transconductance Amplifier (OTA) based compensation network (400) that attempts to stabilize the closed loop. However, after all the compensation methods are tried, the constant-current BCM PFC system still cannot stably operate.

SUMMERY OF THE UTILITY MODEL

The inventors of the present application have realized that the transfer function of the transconductance operational amplifier in the conventional compensation network, including the initial pole and the left half-plane zero, is relatively high in low-frequency gain and not very stable in PFC applications. An object of the embodiments of the present application is to provide a current control type switching power supply circuit, an LED lighting circuit, and a lighting device, so as to solve the problem that a switching power supply control loop that realizes constant current control on the basis of a conventional constant voltage controller that supports high-frequency operation is unstable.

The basic idea proposed by the inventors of the present application is to change the peripheral compensation network of the transconductance operational amplifier/control chip so that the output of the transconductance operational amplifier is coupled to its input, rather than the output being decoupled from the input. The transfer function set in this way has a right half-plane zero point, and compared with the traditional left half-plane, the transfer function set in this way has larger phase margin, lower gain margin and lower crossing frequency, which are beneficial to the stability of the PFC system.

In a first aspect, the present application provides a current-controlled switching power supply circuit comprising

A switching power supply having a power switch and an energy storage and release element that stores energy by a switching operation of the power switch and releases the energy to output the energy;

the current sensing element is used for detecting the current magnitude corresponding to the output energy;

a control chip connected to the power switch for controlling a switching operation of the power switch according to the outputted energy detected by the current sensing element;

the control chip is a voltage control type chip which comprises a voltage feedback input;

the switching power supply circuit further comprises a conversion circuit, wherein the conversion circuit is used for converting the current detected by the current sensing element into a signal amplitude suitable for the voltage feedback input so as to provide the signal amplitude for the control chip; and is

The control chip further comprises a transconductance type operational amplifier comprising a positive input receiving a reference signal (V _ ref), a negative input connected to the voltage feedback input, and an output for coupling to the power switch for controlling the power switch according to the reference signal (V _ ref) and the signal amplitude on the voltage feedback input associated with the current magnitude;

wherein the voltage feedback input:

connected to ground through a first capacitor; and

connected to the output terminal via a compensation network.

In this embodiment, the current control type switching power supply circuit sets a capacitor to ground at the voltage feedback input of the voltage control type chip, and sets the compensation network between the voltage feedback input and the output terminal of the transconductance type operational amplifier, so that the transconductance type operational amplifier can provide a right half-plane zero point, increase the phase margin of the switching power supply, reduce the gain margin of the switching power supply, and reduce the cross-over frequency of the switching power supply, so that the constant current PFC switching power supply based on the voltage control type chip can stably operate.

Optionally, the output terminal of the operational amplifier of transconductance type is decoupled from the ground and coupled to the negative input terminal through the compensation network, the compensation network comprising a second capacitor.

An embodiment of the compensation network is provided, only one capacitor is provided, and the output terminal of the control chip is required to be decoupled from the ground, so as to ensure that the voltage control type chip can be stable for constant current control.

Optionally, the power switch is a gallium nitride high-frequency switch, and the control chip is a high-frequency control chip. The voltage type high-frequency control chip is used for a stable current type high-frequency switching power supply circuit.

Optionally, the capacitance of the first capacitor is nano-farad and the capacitance of the second capacitor is micro-farad.

Optionally, the compensation network further includes a compensation resistor connected in series with the second capacitor between the negative input terminal and the output terminal of the operational amplifier of the transconductance type. The compensation resistor can be used for control loop tuning to match the required phase margin, gain margin and crossover frequency of the switching power supply.

Optionally, the first capacitor and the second capacitor are used to provide a right half-plane zero point for the transconductance type operational amplifier, so as to increase a phase margin of the switching power supply, decrease a gain margin of the switching power supply, and decrease a crossover frequency of the switching power supply.

The first capacitor and the second capacitor provide a right half-plane zero point for the operational amplifier of the transconductance type, and compared with the traditional left half-plane, the right half-plane zero point provides larger phase margin, lower gain margin and lower crossing frequency, which are beneficial to the stability of a PFC system.

Optionally, the switching power supply is a boost, buck or boost topology. Therefore, the switching power supply circuit can be applied to a boost type circuit, a buck type circuit or a boost-buck type circuit, and can realize high-frequency control by using a constant voltage controller in the circuits.

Optionally, the conversion circuit includes a power supply, a first resistor and a second resistor, one end of the first resistor is connected to the power supply, the second end of the first resistor is connected to the voltage feedback input and one end of the second resistor, and the other end of the second resistor is connected to the current sensing element. The conversion circuit is used for providing bias voltage for feedback so that the voltage feedback input of the control chip can identify the feedback signal.

Optionally, the current sensing element includes a detection resistor, the detection resistor is connected in series with a load between the output of the switching power supply and the ground to generate a detection voltage proportional to the magnitude of the current at the output of the switching power supply, and one end of the detection resistor is coupled to the conversion circuit to receive a bias voltage provided by the power supply, and the detection voltage and the bias voltage are added to obtain the signal amplitude suitable for the voltage feedback input.

Optionally, the control chip further includes:

a secondary operational amplifier including a positive input terminal connected to an output terminal of the operational amplifier, a negative input terminal receiving a triangular wave signal, and an output terminal outputting a PWM signal for controlling a switching operation of the power switch;

and the input end of the driving module is connected with the output end of the secondary operational amplifier, and the output end of the driving module is connected to the control end of the power switch, so that the driving capability of the PWM signal is improved to drive the power switch.

A second aspect of the present application provides an LED lighting circuit comprising:

the above switching power supply circuit, and

and the LED is used for receiving the energy provided by the switching power supply of the switching power supply circuit.

A third aspect of the application provides a lighting device comprising the LED lighting circuit as described above.

According to the LED lighting circuit and the lighting equipment, after the energy provided by the switching power supply of the switching power supply circuit is adopted, the high-frequency constant current control can be realized based on the constant voltage control chip, the product cost is reduced, and the reliability of the product is improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

Fig. 1 is a compensation circuit of a constant voltage controller based on a constant current BCM PFC, which is typical in the prior art;

FIG. 2 is a compensation circuit for a typical OTA-based constant current BCM PFC constant voltage controller of the prior art;

fig. 3 is a current-controlled switching power supply circuit provided in the present application;

fig. 4 is a compensation circuit of the OTA in the switching power supply circuit shown in fig. 3.

Fig. 5 is a bode diagram of a conventional compensation circuit in a BCM PFC system and a bode diagram of a compensation circuit of the present application.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.

It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, as used herein, refer to an orientation or positional relationship indicated in the drawings that is solely for the purpose of facilitating the description and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be considered as limiting the present application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

Referring to fig. 3, a first aspect of the present application provides a current-controlled switching power supply circuit, which includes a switching power supply 100, a current sensing element R3, a control chip 200, a converting circuit 300, a first capacitor C1, and a compensation network 400.

The switching power supply 100 is provided with a power switch M1 and a storage and release energy element L1, wherein the storage and release energy element L1 stores energy by the switching operation of the power switch M1 and releases the energy to output energy; the current sensing element R3 is used for detecting the current corresponding to the output energy; the control chip 200 is connected to the power switch M1 for controlling the switching operation of the power switch M1 according to the outputted energy detected by the current sensing element R3; the control chip 200 is a voltage control type chip that includes a voltage feedback input FB; the switching power supply circuit further includes a conversion circuit 300, the conversion circuit 300 is used for converting the current magnitude detected by the current sensing element R3 into a signal amplitude suitable for the voltage feedback input FB to be provided to the control chip 200; and the control chip 200 further comprises a transconductance type operational amplifier 210, the transconductance type operational amplifier 210 comprising a positive input terminal 2 receiving the reference signal V _ ref, a negative input terminal 1 connected to the voltage feedback input FB, and an output terminal 3 for coupling to the power switch M1 for controlling the power switch M1 according to the reference signal V _ ref and a (voltage) signal amplitude associated with a current magnitude on the voltage feedback input FB; wherein, the voltage feedback input FB: is connected to ground GND through a first capacitor C1; and to the output 3 of the operational amplifier 210 of the transconductance type through a compensation network 400.

By arranging a capacitor C1 to ground GND at the voltage feedback input FB of the voltage control type chip and arranging the compensation network 400 between the voltage feedback input FB and the output end 3 of the transconductance type operational amplifier 210, the transconductance type operational amplifier 210 can provide a right half-plane zero point, thereby increasing the phase margin of the switching power supply 100, reducing the gain margin of the switching power supply 100 and reducing the crossing frequency of the switching power supply 100, and enabling the constant-current PFC switching power supply based on the voltage control type chip to stably work.

Alternatively, in contrast to the technique of fig. 1, the output 3 of the control chip 200 is decoupled from ground GND and coupled to the negative input 1 via a compensation network 400, the compensation network 400 comprising a second capacitor C2. An embodiment of the compensation network 400 is provided in which only one capacitor C2 is provided and the output 3 of the control chip 200 is required to be decoupled from ground to ensure that the voltage controlled chip can be stable for constant current control.

Alternatively, the power switch M1 is a gallium nitride high frequency switch and the control chip 200 is a high frequency control chip 200. The voltage type high-frequency control chip is used for a stable current type high-frequency switching power supply circuit.

Alternatively, the capacitance of the first capacitor C1 is nano-farad and the capacitance of the second capacitor C2 is micro-farad.

Optionally, the compensation network 400 further includes a compensation resistor R5, and the compensation resistor R5 and the second capacitor C2 are connected in series between the negative input terminal 1 and the output terminal 3 of the transconductance type operational amplifier 210. The compensation resistor R5 may be zero and may be used for control loop tuning to match the desired phase margin, gain margin, and crossover frequency of the switching power supply 100.

Optionally, the first capacitor C1 and the second capacitor C2 are used to provide a right half-plane zero point for the transconductance type operational amplifier 210, so as to increase the phase margin of the switching power supply 100, decrease the gain margin of the switching power supply 100, and decrease the crossing frequency of the switching power supply 100.

The first capacitor C1 and the second capacitor C2 provide a right half-plane zero point for the transconductance type operational amplifier 210, and provide a larger phase margin, a lower gain margin and a lower crossing frequency compared with the conventional left half-plane, which are beneficial to the stability of the PFC system.

Optionally, the switching power supply 100 is a boost, buck or boost topology. As can be seen, the switching power supply 100 circuit of the present application can be applied to a boost type, a buck type, or a boost-buck type circuit, and can realize high-frequency control using a constant voltage controller in these circuits.

Optionally, the switching circuit 300 includes a power supply Vcc, a first resistor R1 and a second resistor R2, wherein one end of the first resistor R1 is connected to the power supply Vcc, the second end is connected to the voltage feedback input FB and one end of the second resistor R2, and the other end of the second resistor R2 is connected to the current sensing element R3. The converting circuit 300 is used for providing a bias voltage for feedback so that the amplitude of the feedback signal falls in a range in which the control chip 200 can normally respond, so that the voltage feedback input FB of the control chip 200 can correctly respond according to the feedback signal.

Optionally, the current sensing element R3 includes a sensing resistor connected in series with the load between the output of the switching power supply 100 and ground GND to generate a sensing voltage proportional to the magnitude of the current at the output of the switching power supply 100, and one end of the sensing resistor is coupled to the switching circuit 300 to receive the bias voltage provided by the power supply, and the sensing voltage and the bias voltage are superimposed to obtain a signal amplitude suitable for the voltage feedback input FB. Specifically, the detection resistor may be connected in series between the negative terminal of the load (e.g., the cathode of the led D6) and the negative terminal of the output capacitor C0 of the switching power supply 100, and the ground point of the switching power supply 100 is at the negative terminal of the output capacitor C0; alternatively, the detection resistor may be connected in series between the negative terminal of the output capacitor C0 and the source of the power switch M1, and the ground point of the switching power supply 100 is at the source of the power switch M1.

Referring to fig. 2, in the conventional OTA-based compensation circuit, the transfer function:

s is the frequency variable s of the frequency domain of the transfer function 2 pi f, and gm is the transconductance of the open-loop error amplifier, so it can be seen that the transfer function includes an initial pole and a left half-plane zero.

Referring to fig. 4, in the conventional OTA-based compensation circuit, the transfer function:

the transfer function includes an initial pole and a right half-plane zero.

Two kinds of compensation are compared, and the compensation design that this application provided has two characteristics: the low-frequency gain is lower, and the PFC circuit is more stable; with the conventional left half-plane zero, the present application provides a right half-plane zero.

Referring to fig. 5, two simulation results of the compensation circuit are shown, wherein the curve L11 is the phase waveform of the conventional compensation circuit; the curve L12 is a gain waveform of a conventional compensation circuit, the curve L21 is a phase waveform of the compensation circuit, and the curve L22 is a gain waveform of the compensation circuit, it can be seen that the two compensation modes have obvious difference in amplitude-frequency gain-frequency characteristics and phase-frequency characteristics, compared with the waveforms of the curves L11 and L12, the waveforms of the curves L21 and L22 have large phase angle margins, lower crossing frequency and lower low frequency gain, so that the constant current BCM PFC switching power supply based on the voltage control type chip can stably work in high-frequency current control application.

Optionally, the control chip 200 further includes a secondary operational amplifier 220 and a driving module 230. The secondary operational amplifier 220 includes a positive input terminal connected to the output terminal 3 of the transconductance type operational amplifier 210, a negative input terminal receiving a triangular wave signal, and an output terminal for outputting a PWM signal for controlling the switching operation of the power switch M1; the input terminal of the driving module 230 is connected to the output terminal of the secondary operational amplifier 220, and the output terminal DRV of the driving module 230 is connected to the control terminal of the power switch M1, so as to increase the driving capability of the PWM signal to drive the power switch M1. Specifically, the driving module 230 may be an amplifier circuit having VCC as a power supply and a PWM signal as a control signal.

Referring to fig. 3, a second aspect of the present application provides an LED lighting circuit, which includes the above-mentioned switching power supply circuit, and an LED D6 for receiving energy provided by the switching power supply 100 of the switching power supply circuit.

A third aspect of the application provides a lighting device comprising the LED lighting circuit as described above.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (12)

1. A current control type switching power supply circuit comprises

A switching power supply (100) having a power switch (M1) and a storage and release element (L1), the storage and release element (L1) storing energy by a switching operation of the power switch (M1) and releasing energy to output energy;

a current sensing element (R3) for detecting the current magnitude corresponding to the output energy;

a control chip (200) connected to the power switch (M1) for controlling a switching operation of the power switch (M1) according to the outputted energy detected by the current sensing element (R3);

characterized in that said control chip (200) is a chip of the voltage-controlled type, comprising a voltage feedback input (FB);

the switching power supply circuit further comprises a conversion circuit (300), wherein the conversion circuit (300) is used for converting the current magnitude detected by the current sensing element (R3) into a signal amplitude suitable for the voltage feedback input (FB) to be provided for the control chip (200); and is

Said control chip (200) further comprising a transconductance type operational amplifier (210), said transconductance type operational amplifier (210) comprising a positive input receiving a reference signal (V _ ref), a negative input (1) connected to said voltage feedback input (FB), and an output (3) for coupling to said power switch (M1) for controlling said power switch (M1) according to said reference signal (V _ ref) and said signal amplitude on said voltage feedback input (FB) associated with said current magnitude;

wherein the voltage feedback input (FB):

is connected to Ground (GND) via a first capacitor (C1); and

is connected to the output (3) via a compensation network (400).

2. A switching power supply circuit of the current-controlled type according to claim 1, characterized in that the output terminal (3) of said operational amplifier (210) of the transconductance type is decoupled from said Ground (GND) and coupled to said negative input terminal (1) through said compensation network (400), said compensation network (400) comprising a second capacitor (C2).

3. The current-controlled switching power supply circuit according to claim 1, wherein the power switch (M1) is a gallium nitride high-frequency switch, and the control chip (200) is a high-frequency control chip.

4. The current-controlled switching power supply circuit according to claim 2, wherein the capacitance of the first capacitor (C1) is nano-farad and the capacitance of the second capacitor (C2) is micro-farad.

5. A current-controlled switched-mode power supply circuit according to claim 2, characterized in that said compensation network (400) further comprises a compensation resistor (R5), said compensation resistor (R5) being connected in series with said second capacitor (C2) between said negative input terminal (1) and said output terminal (3) of said operational amplifier (210) of the transconductance type.

6. The current-controlled switching power supply circuit according to claim 2, wherein the first capacitor (C1) and the second capacitor (C2) are used to provide a right half-plane zero for the transconductance operational amplifier (210) to increase the phase margin of the switching power supply (100), decrease the gain margin of the switching power supply (100), and decrease the crossing frequency of the switching power supply (100).

7. A current-controlled switching power supply circuit according to claim 1, characterized in that the switching power supply (100) is a boost, buck or boost topology.

8. The current-controlled switching power supply circuit according to claim 1, wherein said switching circuit (300) includes a power supply (Vcc), a first resistor (R1) and a second resistor (R2), one end of said first resistor (R1) being connected to said power supply (Vcc), a second end being connected to said voltage feedback input (FB) and one end of said second resistor (R2), the other end of said second resistor (R2) being connected to said current sensing element (R3).

9. A switching power supply circuit of the current control type according to claim 1 or 8, wherein said current sensing element (R3) includes a detection resistance for being connected in series with a load between an output of said switching power supply (100) and Ground (GND) to generate a detection voltage proportional to a magnitude of a current of the output of said switching power supply (100),

and one end of the detection resistor is coupled to the conversion circuit (300) to accept a bias voltage provided by the power supply,

said detection voltage and said bias voltage are superimposed to obtain said signal amplitude suitable for said voltage feedback input (FB).

10. The current-controlled switching power supply circuit according to claim 1, wherein the control chip (200) further comprises:

a secondary operational amplifier (220) including a positive input terminal connected to the output terminal of the transconductance type operational amplifier (210), a negative input terminal receiving a triangular wave signal, and an output terminal for outputting a PWM signal for controlling a switching operation of the power switch (M1);

and the input end of the driving module (230) is connected with the output end of the secondary operational amplifier (220), and the output end (DRV) of the driving module (230) is connected to the control end of the power switch (M1) for improving the driving capability of the PWM signal so as to drive the power switch (M1).

11. An LED lighting circuit, comprising:

a switching power supply circuit according to any one of claims 1 to 10, and

and the LED is used for receiving the energy provided by the switching power supply of the switching power supply circuit.

12. A lighting device comprising the LED lighting circuit of claim 11.

Images